import sys

import pygame
from bullet import Bullet
from alien import Alien
from time import sleep

def get_number_rows(ai_settings,ship_height,alien_height):
    """計算屏幕可以容納多少行外星人"""
    available_space_y = (ai_settings.screen_height - (3*alien_height)-ship_height)
    number_rows = int(available_space_y/(2*alien_height))
    return number_rows
def get_number_aliens_x(ai_settings,alien_width):
    """計算每行可容納多少個外星人"""
    #外星人間距為外星人寬度
    available_space_x = ai_settings.screen_width-2*alien_width
    number_aliens_x = int(available_space_x/(2*alien_width))
    return number_aliens_x
def create_alien(ai_settings,screen,aliens,alien_number,row_number):
    """創建一個外星人並將其放在當前行"""
    alien = Alien(ai_settings,screen)
    alien_width = alien.rect.width
    alien.x = alien_width+2*alien_width*alien_number
    alien.rect.x = alien.x
    alien.rect.y = alien.rect.height + 2*alien.rect.height*row_number
    aliens.add(alien)
def create_fleet(ai_settings,screen,ship,aliens):
    """創建外星人群"""
    #創建一個外星人，并計算一行可容納多少個外星人    
    alien = Alien(ai_settings,screen)  
    number_aliens_x = get_number_aliens_x(ai_settings,alien.rect.width)     
    number_rows = get_number_rows(ai_settings,ship.rect.height,alien.rect.height)
    #創建第一行外星人
    for row_number in range(number_rows):
       for alien_number in range(number_aliens_x):
           create_alien(ai_settings,screen,aliens,alien_number,row_number)
def fire_bullet(ai_settings,screen,ship,bullets):    
        #創建一顆子彈，並將其加入到編組bullets中
     if len(bullets) < ai_settings.bullets_allowed:
            new_bullet = Bullet(ai_settings,screen,ship)
            bullets.add(new_bullet)
        
def check_keydown_events(event,ai_settings,screen,ship,bullets):
    """響應按鍵"""
    if event.key == pygame.K_RIGHT:
                ship.moving_right = True
    elif event.key == pygame.K_LEFT:
                ship.moving_left = True
    elif event.key ==pygame.K_SPACE:
       fire_bullet(ai_settings,screen,ship,bullets)
    elif event.key == pygame.K_q:
        sys.exit()

def check_keyup_events(event,ship):
    """響應鬆開"""
    if event.key == pygame.K_RIGHT:
                ship.moving_right = False
    elif event.key == pygame.K_LEFT:
                ship.moving_left = False    
def check_events(ai_settings,screen,stats,play_button,ship,aliens,bullets):
    """響應按鍵和鼠標事件"""
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            sys.exit() 
        elif event.type ==pygame.MOUSEBUTTONDOWN:
            mouse_x,mouse_y = pygame.mouse.get_pos()
            check_play_button(ai_settings,screen,stats,play_button,ship,aliens,bullets,mouse_x,mouse_y)
        elif event.type == pygame.KEYDOWN:
            check_keydown_events(event,ai_settings,screen,ship,bullets)                    
        elif event.type == pygame.KEYUP:
            check_keyup_events(event,ship)
def check_play_button(ai_settings,screen,stats,play_button,ship,bullets,aliens,mouse_x,mouse_y):
        """在玩家單擊play按鈕時開始新遊戲"""
        button_clicked = play_button.rect.collidepoint(mouse_x,mouse_y)
        #collidepoint 判断点是否在矩形内部
        if button_clicked and not stats.game_active:
           #重置遊戲設置
           ai_settings.initialize_dynamic_settings()
            
           # 隱藏光標
           pygame.mouse.set_visible(False)
           # 重置遊戲統計信息
           stats.reset_stats()
           stats.game_active = True
           # 清空外星人和子彈列表
           aliens.empty()
           bullets.empty()

           #創建一群新的外星人，並讓飛船居中
           create_fleet(ai_settings,screen,ship,aliens)
           ship.center_ship()
def update_screen(ai_settings,screen,stats,sb,ship,aliens,bullets,play_button):     
    screen.fill(ai_settings.bg_color)
    #在飛船和外星人後面重繪所有子彈
    for bullet in bullets.sprites():
        bullet.draw_bullet()
    ship.blitme()
    aliens.draw(screen)
    # 顯示得分
    sb.show_score()
    #如果遊戲處於非活動狀態，就顯示Play按鈕
    if not stats.game_active:
        play_button.draw_button()
        
    #讓最近繪製的屏幕可見
    pygame.display.flip()
def update_bullets(ai_settings,screen,ship,aliens,bullets):
    #刪除已消失的子彈
    bullets.update()
    for bullet in bullets.copy():
        if bullet.rect.bottom <= 0:
            bullets.remove(bullet)
    check_bullet_alien_collisions(ai_settings,screen,ship,aliens,bullets)
    
def check_bullet_alien_collisions(ai_settings,screen,ship,aliens,bullets):
    """響應外星人與子彈碰撞"""
    #檢查是否有子彈擊中外星人
    #若擊中，將子彈與外星人都刪除
    collisions = pygame.sprite.groupcollide(bullets,aliens,True,True)
    if len(aliens)==0:
        #刪除現有的子彈并新建一群外星人,加快遊戲節奏
        bullets.empty()
        ai_settings.increase_speed()
        create_fleet(ai_settings,screen,ship,aliens)
def check_fleet_edges(ai_settings,aliens):
    """有外星人到達邊緣時採取相應的措施"""
    for alien in aliens.sprites():
        if alien.check_edges():
            change_fleet_direction(ai_settings,aliens)
            break
def change_fleet_direction(ai_settings,aliens):
    """將整外星人下移，并改變他們的方向"""
    for alien in aliens.sprites():
        alien.rect.y += ai_settings.fleet_drop_speed
    ai_settings.fleet_direction+=-1
def ship_hit(ai_settings,screen,stats,ship,aliens,bullets):
    """響應被外星人撞到的飛船"""
    if stats.ships_left>0:
       # 將ship_left減1
       stats.ships_left -= 1
       #清空外星人列表和子彈列表
       aliens.empty()
       bullets.empty()

       #創建一群新的外星人，並將飛船放到屏幕低端中央
       create_fleet(ai_settings,screen,ship,aliens)
       ship.center_ship()

       #暫停
       sleep(0.5)
    else:
        stats.game_active = False
        pygame.mouse.set_visible(True)
def check_aliens_bottom(ai_settings,stats,screen,ship,aliens,bullets):
    """檢查是否有外星人道大屏幕低端"""
    screen_rect = screen.get_rect()
    for alien in aliens.sprites():
        if alien.rect.bottom>=screen_rect.bottom:
            #像飛船被撞倒一樣處理
            ship_hit(ai_settings,screen,stats,ship,aliens,bullets)
            break

def update_aliens(ai_settings,stats,screen,ship,aliens,bullets):
    """
    檢查是否有外星人位於屏幕邊緣，并更新鄭群外星人的位置
    """
    check_fleet_edges(ai_settings,aliens)
    aliens.update()
    # 檢測外星人和飛船之間的碰撞
    if pygame.sprite.spritecollideany(ship,aliens):
        ship_hit(ai_settings,screen,stats,ship,aliens,bullets)
    check_aliens_bottom(ai_settings,stats,screen,ship,aliens,bullets)
